Originally Posted by Britt
I've never heard of a vet worming your horse for you... :/
I've always wormed all of mine myself, my entire family and everyone I know worms their horses themselves. We just buy hat type of wormer we need for that particular season at the local tack or feed or TSC store and give it to them ourselvs.
Deworming a horse isn't hard, but choosing the right dewormer is important. There isn't a "season" for worms but you do want to use an ivermectin product in the fall for bots. This is because it will catch them before they begin to migrate. Maybe that's what you're thinking?
To the OP, it is best to bring a fecal sample to the vet if this horse is new to you and you don't know his deworming history. This way they can tell you which parasites are present and which dewormer you should use. If he has a particularly high number of parasites you may need to deworm repeatedly for a much longer period of time, but if he doesn't have a lot then it's a waste of time and money to do it that way "just in case".
In general you should deworm 4 times per year. You want to use a praziquantal product for tapes, pyrantel for rounds, and ivermectin for bots. I don't know all the brand names but all the dewormers list the generic drug name so you can read the label and know what you're getting. AAEP also has a great chart on when and what to deworm with. Good luck!
And if you have any border collies, keep them well clear of your ivermectin!!!